Regional fractionation and dominant frequency in persistent atrial fibrillation: effects of left atrial ablation and evidence of spatial relationship

AIMS: The aim was to study regional fractionation and dominant frequency (DF) to determine if any relationship exists between the two parameters and also to assess the impact of limited left atrial ablation. METHODS AND RESULTS: Patients undergoing catheter ablation of persistent AF using three-dimensional navigation were studied. Regional left atrial electrograms were analysed in the frequency domain by assessing DF and organization index (OI), and for degree of fractionation [using complex fractionated electrograms (CFE)-mean] before and after circumferential pulmonary vein and left atrial roof ablation. Twenty-three patients with persistent AF were studied. After ablation, global CFE-mean increased [100 ± 5 to 147 ± 11 ms (P= 0.0003)], DF decreased [6.1 ± 0.2 to 5.3 ± 0.2 Hz (P= 0.0003)], and OI was unchanged [0.27 ± 0.01 to 0.26 ± 0.02, (P= 0.70)]. Comparing sites close to and distant from ablation lines, percentage change in CFE-mean was 94 ± 10 vs. 37 ± 6% (P< 0.0001), DF change was -13 ± 3 vs.-12 ± 2% (P= 0.98), and OI change was 3 ± 6 vs. 10 ± 5% (P= 0.75), respectively. There was modest correlation between CFE-mean and DF points prior to ablation (r = -0.33, P< 0.0001) which was reduced following left atrial ablation (r = -0.24, P= 0.005). CONCLUSIONS: Left atrial ablation reduces global left atrial DF and decreases the degree of fractionation. Complex fractionated electrograms-mean and DF appear to share only modest spatial correlation and are affected to different extents by ablation, suggesting that they are either separate entities or reflect different components of the same substrate.